Fluid adsorption systems for producing an enriched fluid product are well known. For example, gases such as oxygen or nitrogen can be produced by passing air under pressure through regenerative adsorbing beds that remove one or more of the major gas components therefrom and produce an enriched recovery of a remaining gas component. Examples of such systems are described in U.S. Pat. No. 4,698,075 and the patents cited therein, all of which are incorporated herein by reference.
In such systems a plurality of adsorption beds containing zeolite adsorbent materials are provided. The beds are interconnected by flow control systems so that each bed is operated through repeated cycles, including a pressurized adsorption phase and a depressurized regeneration phase. During the pressurized adsorption phase, air under pressure is supplied to a given bed which, for example, absorbs the nitrogen component of the air passing therethrough so that an oxygen enriched component is produced.
In order to provide continued production, a portion of the enriched gas product from one bed is recirculated through a depressurized companion bed to remove previously adsorbed nitrogen therefrom. This regenerates the depressurized bed for a subsequent pressurized adsorption operation. The regeneration process requires recirculation of only a portion of the beneficiated gas produced by the companion bed and the remaining portion of that gas is removed as a product of the system.
During the regeneration of the bed, the gas present within the bed has been permitted to exhaust to the atmosphere as waste and no attempt has been made to utilize the waste gas within the system.